The Kneeslider just passed its 7 year anniversary and one of the most enjoyable benefits is getting to see the progress some of the projects we covered years ago have made since we first brought them to your attention. I just received an email from J. Jacek Synakiewicz, he’s the JJS in JJS Design, the Polish company behind the JJ2S X4 500 we wrote about way back in 2008. He wanted everyone to know they’re still moving forward and have a prototype under construction which was just exhibited at “Design in Poland – Transition to Modernity” in Geneva, Switzerland.
For those of you just tuning in, the motorcycle is built around a 4 cylinder, 500cc 2 stroke “X” configuration engine, sort of a 4 cylinder radial. The previous computer renderings looked great and the bike now under construction by GG Tech looks every bit as good, which means the photos are quite amazing.
JJ says their goal is to have the bike finished some time next year so it can be displayed at one of the major European motorcycle shows.
This is one of those projects that just looks so cool and has such neat technology you really want it to succeed. Right now they are looking for investors to help bring it all together. I hope we see the finished bike next year wowing the crowds all over Europe.
Link: JJS Design
Link: JJS X4 Gallery
Link: Design in Poland
UPDATE: I’m adding this animation below to show how the X4 moves.
The translated version of how it works is here.
Tyler says
Awesome, I love getting updates to older entries, thanks Paul.
Nice to see something come out of the vaoprware closet and into reality.
B50 Jim says
Love that engine! No reason a motorcycle engine has to be inline, a boxer or a V. Well thought-out architecture — the engine serves as the main structure and all the other bits hang on using minimal hardware. I hope they can get some backing so they can develop that engine beyond the one-off, machined-from-billet item we see here. I’d love to hear this one running!
Racetrack Style says
It will be interesting to see how the 2-stroke engine characteristics work with this ‘frame’ structure. Ducati is working diligently to figure out how to make a similar frame structure work with their 4 cylinder GP bike (using cf or aluminum).
Great-looking bike! An audio clip would really stoke interest.
QrazyQat says
My gosh. Tiny. There’s a lot of leeway there to build the seat etc. any size. Short people might even have a bike they don’t need platform shoes to ride.
Marcel says
Was just telling a friend about the X4 engine a few days ago.Thanks for the update,. It looks fantastic, would love to see some close up pics
2stroker says
Where is the expansion chamber?
Marcel says
Just saw the close ups on their web site – beautiful exhaust plumbing
Shawn says
That’s an awesome looking little frame. I’d love to have a frame that small wrapped around a 4-500 cc 4-stroke twin, like the one used in the Canadian Market Ninja 400R. I bet you could make a nice modern take on a cafe racer with such a sparse frame. (Banana swingarms and twin-spar chassis or overdone full-length trellises just don’t do it for me visually). The X4 looks pretty cool as well.
Paulinator says
Wow!!! I looked at the patent (I wish I could read Polish). This is a very clever engine. The crank case is isolated from the induction cycle – like a 4-stroke – so multiple cylinders are actually a benefit becuase they will equalize pressure. I guess they are confident with the flow dynamics since they left off the expansion chambers.
Nice original bike. Can’t wait for the sound-track and performance numbers!!!
GenWaylaid says
Yes, I was puzzled about the induction arrangement until I realized it was direct-injected. Velocity stack + reed block is all they need. Personally I would have added a supercharger for enhanced scavenging. With no resonant chambers on the intake or exhaust, the current design may not “breathe” as well as it could.
akaacount says
I’m afraid I’m not following how the thing runs. It’s direct injection, so no fuel going through the intake porting, got it. But, apparently the crankcases are connected, so no compression/vacuum for air (and oil mix?) to flow into the combustion chamber. Or is there a separate chamber under the pistons exposed to the reed valves?
Paul Crowe - "The Kneeslider" says
Check out the Google translate version of the explanation, here.
I also added an animation at the end of the post above.
Chris says
Is it real? or is it just a cast mock up. I like the idea of something new, but find my self scratching my head. At this juncture I am will to stick my neck out and say it is a non running mock up. Very interesting design.
FREEMAN says
Hopefully they get to build their bike and we’ll be able to see it complete. Keep up the good work. Would love to see it in more of a kinetic fashion when done, too.
sebatron says
The last shot shows what does look like an expansion chamber.
Can’t wait to hear it. Might have to make a trip to the motherland and see if I can wangle a testride when it’s done.
Only flag I can raise is the rake looks really conservative from these photos, unless the suspension is already set for weight that isn’t there (tank, seat, subframe etc) ?
Jack Meoph says
I want to drink beer with that guy in the sweater, and then go smash in some heads with a hammer.
Geaff says
The bike looks great and like others have said, the update is also great.
Paul I have read your site almost every day for years now, I have never commented but more importantly I have never said Thank You for the effort you put in to this terrific site. So Thank You Very Much from Geoff in Australia.
akaacount says
Beautiful. New desktop wallpaper.
Les says
A nice surprise! This has been one of my fave concept bikes for a long while. Glad to see it’s being fabricated 🙂
JOhndo says
Freakin awesome.
Jon says
That is the sexiest beast I’ve seen in years. I’d certainly throw a leg over it. I still remember how fun/terrifying the Kawasaki triples were. Now I just need to convince my wife we need to move to Poland…
jim sadler says
Yet we have no clue as to how the intake charge will work. Two strokes tend to be built around the intake charge being compressed underneath the piston and the charge ported when the intake is open. Isolating the crank case from the intake means either a low powered engine or a supercharger.
In other words that old three cylinder Kaw may be hard to beat. And for those in the know the 750 Mach IV Kaws already had a four cylinder two stroke replacement that made it to the states but was sent back to Japan. They did not want a 4 cyl. 2 stroke in competition with the about to be released Z1 – 900 Kaw.
Among other things I owned a drilled out 750 Kaw with full race chambers and carbs that were huge. The pucker factor was very high.
OMMAG says
All this time and still no working prototype? The engine? The bike?
Neither…?
Am I wrong or not reading this correctly?
Marvin says
To be fair, its still a lot more than I have built in the last three years, Its probably just slowly coming together because they are doing other work to keep body and soul together. The younger bloke looks about the right age to have a young family. They may also of course have had to stop and save for bought out parts or wait for a bargain price so they could get what they want. We often moan on here about new models of motorcycles that are just tweaked versions of older ones. Even the big motorcycle makers tend not to do too many bikes with brand new engines and brand new frames in one go because it even takes them a long time.
John Ellwood says
Its very clever. The pairs of upside down stepped pistons are attached to a scotch yoke sort of arrangement. There will be no piston slap, longer duration at TDC giving a better burn, near perfect balance, no heavy flywheels, built in supercharging from the stepped part (and still enabling the racing class cc size to be adhered to).
The design is fantastic, cant wait to see one in the flesh. The only negative feeling is i dont think there`s any racing class for it as tptb have eliminated the 2 strokes.
Long live 2 strokes.
Gary says
Ditto on the last comment. What will happen when the pollution Nazis get ahold of this. I understand that oil will not need to be burned in as great a quantity as before if at all but since exhaust and intake are not completely separated events won’t raw fuel escape at some point? Will this be the same as intake and exhaust valve overlap is in four-strokers now? Will the mass of the piston be comparable to conventional pistons?
jim sadler says
Direct injection as well as a good blower will likely get this thing past the EPA. Instead of injecting into the air stream just inject the gasoline directly into the cylinder after the exhaust port is sealed off. More oxygen from a blower and a clean burn is likely. One issue is whether one air intake is always open so the air charge has some place to go.
Dave says
Am I looking at it right? It looks like the pistons have built in moving sleeves so its a sleeve valve of some sort. Agreed its likely to have perfect balance but theres a lot of complex metal work in there.
A more simple design with the same X format could have a single throw crank with all four con-rods on the one crank pin. Not easy with wide plain bearings but with narrow roller bearing big ends (normal 2 stroke style) it would (should?) be possible.
Having a constant volume crankcase it would need a blower (probably), but DI injection would manage the fuel supply and normal 2 stroke oil injection would keep it lubricated.
It would be perfect in the third world where disposing used sump oil is a serious pollution problem. 4 Strokes use a huge amount. 2 strokes (cleanly) burn their lube oil and overall use less than a similar 4 stroke.
Dave says
What i see in the engine design is the “piston” in a fixed position and the ported sleeve connected to the rod slideing in a common bore so one sleeve on the down stroke super charges its partner .
Steven says
This is not a new engine design. It is basically a copy of the Bourke engine designed and built in the 1930s by Russell Bourke. To understand how it works, http://en.wikipedia.org/wiki/Bourke_engine or visit http://bourke-engine.com/general_info.htm
Jacek says
The engine JJ2S X4 is similar to the Bourke engine only that both work in the two stroke system.
To write such comment should be verified first exactly knowledge on the subject.